CVE-2026-50012: squid Input Validation Flaw — Fix

Description

Squid is a caching proxy for the Web. Prior to 7.6, due to an improper input validation bug in cache digest reply handling (peerDigestSwapInMask in src/peer_digest.cc), Squid is vulnerable to a heap-based buffer overflow: a cache digest's on-the-wire size may be larger than the mask_size declared within the digest, so a trusted peer sending a maliciously crafted reply to a cache_digest request message can trigger the overflow. This attack is limited to Squid instances compiled with the --enable-cache-digests option and configured with cache_peer entries. This issue is fixed in version 7.6.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H

EPSS — Exploit Prediction

0.0225

Probability of exploitation

0.81%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-122 CWE-122

Affected Products

Vendor	Product	Versions
squid-cache	squid	< 7.6

References

Advisories & Patches

https://github.com/squid-cache/squid/commit/19fcfe922717c8b255270c032dcde4071c003bcd https://github.com/squid-cache/squid/pull/2423 https://github.com/squid-cache/squid/security/advisories/GHSA-5vmx-9x64-9284

Other References

https://github.com/squid-cache/squid/releases/tag/SQUID_7_6

Frequently Asked Questions

What is CVE-2026-50012? +

Squid is a caching proxy for the Web. Prior to 7.6, due to an improper input validation bug in cache digest reply handling (peerDigestSwapInMask in src/peer_digest.cc), Squid is vulnerable to a heap-based buffer overflow: a cache digest's on-the-wire size may be larger than the mask_size declared within the digest, so a trusted peer sending a maliciously crafted reply to a cache_digest request message can trigger the overflow. This attack is limited to Squid instances compiled with the --enable-cache-digests option and configured with cache_peer entries. This issue is fixed in version 7.6. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-50012? +

CVE-2026-50012 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0225, placing it in the 1th percentile for exploitation probability.

What products are affected by CVE-2026-50012? +

CVE-2026-50012 affects products from squid-cache, specifically: squid. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-50012? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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